When someone says “window box,” what images first pop into your mind? Old World, pretentious, charming, expensive? Perhaps you think of these gussied-up containers as high maintenance, or maybe you simply write them off as another wacky sport in the world of competitive gardening. Yet, could it be that you would really like to try them, but have no idea where to begin?

Properly installed window boxes increase the gardening space in minuscule landscapes and places with less than perfect soil. They are also a relatively inexpensive way to add visual interest to an otherwise plain structure. Consider the side of a garage with a single pedestrian window: Add a box of flowers, and it is now a focal point. Window boxes also break the monotony of nearly identical buildings, such as town or row houses, and lend visual harmony and rhythm. What makes window boxes truly special is that many are eye-level gardens, and nothing beats a nose-to-petal tête-à-tête.

IT STARTS WITH THE CONTAINER
The secret to a structurally and horticulturally successful window box is good drainage. Not only must water move out of the container to prevent root rot, but it is imperative that moisture does not get trapped between the box and the building. Frank Lauro, Jr., a contractor in Charleston, S.C., knows firsthand what a small amount of extra moisture can do to structures. Having spent the past 20 years restoring and preserving historic buildings in Charleston, he has centered much of his work on water-damage remediation.

He has also designed and installed window boxes for clients. If window boxes were automobiles, Lauro’s would be Bentleys. Starting with treated lumber, he lines the interior and exposed upper edges with copper sheeting and plumbs them with irrigation tubes and water discharge pipes. One of his most elegant and durable creations has graced a downtown brick-and-stucco establishment in Charleston since 1995.

If such custom-made luxury isn’t for you, containers crafted from wood, cast stone, ceramic, terra-cotta, plastic, metal or fiberglass are readily available. Some manufacturers also offer brackets, braces and mounting hardware to use with their products. Keep in mind that the box must be placed away from the main structure to avoid water damage and to accommodate airflow. Boxes that are placed up against a building hold moisture, which not only attracts insects, but also acts as a giant petri dish for mold and mildew.

Ensure that the window box itself provides good drainage. Like some of Lauro’s window boxes, many are equipped with vents for drainpipes. Many merely have holes drilled in the bottom. Look for abundant and evenly spaced holes, not just a couple in the middle. If you intend to install a window box that includes fittings for an irrigation system, make sure the water trickles into the soil and not down your siding.

FILLING IT UP
Before selecting your flora, consider the environmental conditions such as heat and sun intensity. Any window box plant that faces the hot afternoon sun or receives relentless blasts of heat from an air-conditioner exchange unit rarely survives. The reflective light from window glass also increases thermal intensity. Even June transplants such as melampodium, pentas, portulaca and vinca don’t have a prayer in hot weather exacerbated by the thermal punch received by window boxes.

On the other hand, if you are faced with scant sunlight, combine houseplants such as ZZ plant (Zamioculcas zamiifolia), pothos or aspidistra. Crowd them together with shade-loving ferns for a jungle effect.

What makes some window boxes stand out more than others? Great designs have a creative blend of color, height variation and contrasting textures collectively spilling and spreading away from the container. An exceptional one is also full of surprises, such as a vine that has been coaxed to twine upward instead of flowing toward the ground, or combining unexpected plants such as orchids with conventional flora.

It also pays to explore beyond the annual and perennial sections of a garden center. Consider the potential of ornamental grasses, herbs, tropical plants and dwarf shrubs. Hothouse mophead hydrangeas have become popular choices for window boxes, and dwarf cedar and boxwood offer playful alternatives, if positioned off center. In other words, the real trick to coming up with an eye-catching display is to “think outside the box.”

This article appeared in a previous issue of a State-by-State Gardening publication.
Photos by PJ Gartin.

The views and opinions expressed in this article are those of the author alone and do not necessarily reflect the views or opinions of State-by-State Gardening, its parent company or affiliates. The author is solely responsible for all content. Our articles are only meant to educate and entertain our readers. We are not medical professionals and cannot recommend the ingestion or topical application of any herbal remedy, poultice, tea, etc. Please consult a medical professional before ingesting any plant.